Such a system is described, in particular, in document FR-A-2 684 249.
Nevertheless, in certain applications, and in particular when the modular assembly as mentioned above is intended for powering an electric vehicle, it can be particularly important for very accurate measurements to be available to such a system. Such measurements can improve management of the modular assembly while it is in use, in particular when a high level of reliability and long life are required and when there also exists major risks in the event of wrong operation, e.g. in the event of cells in a modular set being overcharged during charging. It is particularly important to be able to verify that the measurement means are operating properly, e.g. in order to be sure that they are continuing to give accurate results and consequently to be in a position to recalibrate them, should that be necessary.
Document EP-A-0 121 547 describes a charging regulator for a modular set of electrochemical cells intended more particularly for emergency use, and consequently requiring to be maintained almost constantly recharged to an optimum value. Each cell is provided with an individual circuit connected to the power supply terminals of the cell and measuring the voltage between those terminals for the purpose of regulating the charging current applied to the cell by progressively bypassing charging current through a circuit external to the cell, starting from a determined bypass trigger voltage, so as to bring the cell safely to its optimum charge. Such a circuit is nevertheless ill-adapted to obtaining optimum charge in a cell that forms part of a modular set which is necessarily subjected to large variations in state of charge, as is particularly likely to be the case of a set used as the power supply for an electric vehicle.